Power converter having negative current detection mechanism

Abstract

A power converter with a negative current detection mechanism is provided. A negative current detecting circuit includes a first operational amplifier, a first transistor and a second transistor. A non-inverting input terminal of the first operational amplifier is connected to a second terminal of a sense resistor. An inverting input terminal of the first operational amplifier is connected to a first terminal of a first capacitor. Control terminals of the first and second transistors are connected to an output terminal of the first operational amplifier. A first terminal of the first transistor is connected to the second terminal of the sense resistor. A second terminal of the first transistor is grounded. A first terminal of the second transistor is connected to the inverting input terminal of the first operational amplifier and the first terminal of the first transistor. A second terminal of the second transistor is grounded.

What is claimed is: 
     
       1. A power converter having a negative current detection mechanism, comprising:
 a high-side switch, wherein a first terminal of the high-side switch is connected to an input voltage, and a control terminal of the high-side switch is connected to a triggering circuit; 
 a low-side switch, wherein a first terminal of the low-side switch is connected to a second terminal of the high-side switch, a second terminal of the low-side switch is grounded, and a control terminal of the low-side switch is connected to the triggering circuit; 
 an inductor, wherein a first terminal of the inductor is connected to a node between the second terminal of the high-side switch and the first terminal of the low-side switch, 
 an output capacitor, wherein a first terminal of the output capacitor is connected to a second terminal of the inductor, and a second terminal of the output capacitor is grounded; 
 a first resistor, wherein a first terminal of the first resistor is connected to the first terminal of the inductor; 
 a first capacitor, wherein a first terminal of the first capacitor is connected to a second terminal of the first resistor, and a second terminal of the first capacitor is connected to the second terminal of the inductor; 
 a sense resistor, wherein a first terminal of the sense resistor is connected to the second terminal of the inductor; and 
 a negative current detector circuit, including:
 a first operational amplifier, wherein a non-inverting input terminal of the first operational amplifier is connected to a second terminal of the sense resistor, and an inverting input terminal of the first operational amplifier is connected to the first terminal of the first capacitor; 
 a first transistor, wherein a control terminal of the first transistor is connected to an output terminal of the first operational amplifier, a first terminal of the first transistor is connected to the non-inverting input terminal of the first operational amplifier, and a second terminal of the first transistor is grounded; and 
 a second transistor, wherein a control terminal of the second transistor is connected to the output terminal of the first operational amplifier, a first terminal of the second transistor is coupled to a common voltage, the first terminal of the second transistor is connected to the non-inverting input terminal of the first operational amplifier and the first terminal of the first transistor, and a second terminal of the second transistor is grounded. 
 
 
     
     
       2. The power converter with the negative current detection mechanism according to  claim 1 , wherein the negative current detector circuit further includes a first current mirror circuit, an input terminal of the first current mirror circuit is connected to the first terminal of the second transistor, and an output terminal of the first current mirror circuit is a first output terminal of the power converter. 
     
     
       3. The power converter with the negative current detection mechanism according to  claim 2 , wherein the first current mirror circuit includes a third transistor and a fourth transistor, a first terminal of the third transistor and a first terminal of the fourth transistor are coupled to the common voltage, a second terminal of the third transistor is connected to the first terminal of the second transistor, a control terminal of the third transistor and a control terminal of the fourth transistor, and a second terminal of the fourth transistor is the first output terminal of the power converter with the negative current detection mechanism. 
     
     
       4. The power converter with the negative current detection mechanism according to  claim 3 , further comprising:
 a negative current limiting circuit including a negative current determining circuit, wherein the negative current determining circuit is connected to the second terminal of the fourth transistor and an input terminal of the triggering circuit, and the negative current determining circuit is configured to output a current limiting signal to the triggering circuit to control the triggering circuit to turn on or off the high-side switch and the low-side switch according to a current flowing through the second terminal of the fourth transistor. 
 
     
     
       5. The power converter with the negative current detection mechanism according to  claim 3 , further comprising:
 a clamping circuit connected to the non-inverting input terminal of the first operational amplifier, the first terminal of the first transistor, the first terminal of the second transistor and the second terminal of the third transistor. 
 
     
     
       6. The power converter with the negative current detection mechanism according to  claim 5 , further comprising:
 a negative current limiting circuit including a negative current determining circuit, wherein the negative current determining circuit is connected to the second terminal of the fourth transistor and an input terminal of the triggering circuit, the negative current determining circuit is configured to output a current limiting signal to the triggering circuit to control the triggering circuit to turn on or off the high-side switch and the low-side switch according to a current flowing through the second terminal of the fourth transistor. 
 
     
     
       7. The power converter with the negative current detection mechanism according to  claim 5 , wherein the clamping circuit includes an operational amplifier and a transistor, wherein a first terminal of the transistor is connected to the second terminal of the third transistor, a non-inverting input terminal of the operational amplifier is connected to the first terminal of the first transistor and the non-inverting input terminal of the first operational amplifier, an inverting input terminal of the operational amplifier is connected to the first terminal of the second transistor and a second terminal of the transistor, and an output terminal of the operational amplifier is connected to a control terminal of the transistor. 
     
     
       8. The power converter with the negative current detection mechanism according to  claim 7 , further comprising:
 a negative current limiting circuit including a negative current determining circuit, wherein the negative current determining circuit is connected to the second terminal of the fourth transistor and an input terminal of the triggering circuit, and the negative current determining circuit is configured to output a current limiting signal to the triggering circuit to control the triggering circuit to turn on or off the high-side switch and the low-side switch according to a current flowing through the second terminal of the fourth transistor. 
 
     
     
       9. The power converter with the negative current detection mechanism according to  claim 8 , wherein the negative current limiting circuit further includes a second operational amplifier, a non-inverting input terminal of the second operational amplifier is connected to the second terminal of the fourth transistor, an inverting input terminal of the second operational amplifier is coupled to a reference voltage, and an output terminal of the second operational amplifier is connected to an input terminal of the negative current determining circuit. 
     
     
       10. The power converter with the negative current detection mechanism according to  claim 9 , wherein the negative current limiting circuit further includes a resistor, a first terminal of the resistor is connected to the non-inverting input terminal of the second operational amplifier, and a second terminal of the resistor is grounded. 
     
     
       11. The power converter with the negative current detection mechanism according to  claim 1 , further comprising:
 a positive current detector circuit including a third operational amplifier and a fifth transistor, a non-inverting input terminal of the third operational amplifier is connected to the first terminal of the first capacitor, an inverting input terminal of the third operational amplifier is connected to the second terminal of the sense resistor, an output terminal of the third operational amplifier is connected to a control terminal of the fifth transistor, a first terminal of the fifth transistor is coupled to the common voltage, and a second terminal of the fifth transistor is connected to the inverting input terminal of the third operational amplifier. 
 
     
     
       12. The power converter with the negative current detection mechanism according to  claim 11 , wherein the positive current detector circuit further includes a second current mirror circuit, an input terminal of the second current mirror circuit is connected to the first terminal of the fifth transistor, and an output terminal of the second current mirror circuit is a second output terminal of the power converter with the negative current detection mechanism. 
     
     
       13. The power converter with the negative current detection mechanism according to  claim 12 , wherein the second current mirror circuit includes a sixth transistor and a seventh transistor, a first terminal of the sixth transistor and a first terminal of the seventh transistor are coupled to the common voltage, a second terminal of the sixth transistor is connected to the first terminal of the fifth transistor, a control terminal of the sixth transistor and a control terminal of the seventh transistor, and a second terminal of the seventh transistor is the second output terminal of the power converter with the negative current detection mechanism.